Digital Signature Algorithm

The Digital Signature Algorithm (DSA) is a public-key cryptosystem and Federal Information Processing Standard for digital signatures, based on the mathematical concept of modular exponentiation and the discrete logarithm problem. In a digital signature system, there is a keypair involved, consisting of a private and a public key. In this system a signing entity that declared their public key can generate a signature using their private key, and a verifier can assert the source if it verifies the signature correctly using the declared public key. DSA is a variant of the Schnorr and ElGamal signature schemes.

The National Institute of Standards and Technology (NIST) proposed DSA for use in their Digital Signature Standard (DSS) in 1991, and adopted it as FIPS 186 in 1994. Five revisions to the initial specification have been released. The last standard, however, removed NIST's approval for DSA signature generation.